Infection of Nigrospora nonsegmented RNA Virus 1 Has Important Biological Impacts on a Fungal Host

Abstract

Nigrospora nonsegmented RNA virus 1 (NoNRV1) has been reported previously in the fungus Nigrospora oryzae, but its biological effects on its host are unknown. In this work, we isolated a strain 9-1 of N. oryzae from a chrysanthemum leaf and identified NoNRV1 infection in the isolated strain. The genome sequence of NoNRV1 identified here is highly homologous to that of the isolate HN-21 of NoNRV1 previously reported; thus, we tentatively designated the newly identified NoNRV1 as NoNRV1-ZJ. Drug treatment with Ribavirin successfully removed NoNRV1-ZJ from the strain 9-1, which provided us with an ideal control to determine the biological impacts of NoNRV1 infection on host fungi. By comparing the virus-carrying (9-1) and virus-cured (9-1C) strains, our results indicated that infection with NoNRV1 promoted the pigmentation of the host cells, while it had no discernable effects on host growth on potato dextrose agar plates when subjected to osmotic or oxidative stress. Interestingly, we observed inhibitory impacts of virus infection on the thermotolerance of N. oryzae and the pathogenicity of the host fungus in cotton leaves. Collectively, our work provides clear evidence of the biological relevance of NoNRV1 infection in N. oryzae, including pigmentation, hypovirulence, and thermotolerance.

Community Series in Plants and Microbial Communities: Diversity, Pathogens and Biological Control, Volume II

“…Most known mycoviruses cryptically infect their hosts, but some mycoviruses can greatly affect their host, either by hypovirulence or hypervirulence. For example, the Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 can convert its host, Sclerotinia sclerotiorum, from a typical necrotrophic pathogen into a beneficial endophytic fungus (Zhang et al, 2020); infection with Nigrospora nonsegmented RNA virus 1 led to hypovirulence of Nigrospora oryzae on cotton leaves (Wang et al, 2022b); the Diaporthe pseudophoenicicola chrysovirus 1 can confer hypovirulence to the fungal host of Diaporthe pseudophoenicicola (Xu et al, 2022); and the virulence of Leptosphaeria biglobosa can be increased by the Leptosphaeria biglobosa quadrivirus 1 (Shah et al, 2020). The role of mycoviruses in the pathogenesis of fungi was welldiscussed in previous papers Bian et al, 2020;Kotta-Loizou, 2021).…”

Molecular characterization of a novel partitivirus isolated from Rhizoctonia solani

“…Most known mycoviruses cryptically infect their hosts, but some mycoviruses can greatly affect their host, either by hypovirulence or hypervirulence. For example, the Sclerotinia sclerotiorum hypovirulence–associated DNA virus 1 can convert its host, Sclerotinia sclerotiorum , from a typical necrotrophic pathogen into a beneficial endophytic fungus (Zhang et al, 2020 ); infection with Nigrospora non-segmented RNA virus 1 led to hypovirulence of Nigrospora oryzae on cotton leaves (Wang et al, 2022b ); the Diaporthe pseudophoenicicola chrysovirus 1 can confer hypovirulence to the fungal host of Diaporthe pseudophoenicicola (Xu et al, 2022 ); and the virulence of Leptosphaeria biglobosa can be increased by the Leptosphaeria biglobosa quadrivirus 1 (Shah et al, 2020 ). The role of mycoviruses in the pathogenesis of fungi was well-discussed in previous papers (Abdoulaye et al, 2019 ; Bian et al, 2020 ; Kotta-Loizou, 2021 ).…”